A method for preparing an inclined grating

Abstract

The application relates to the field of micro-nano manufacturing technology and solves the problems of low yield and high cost of the existing preparation method, and the method comprises the following steps: preparing a grating structure with an included angle of 90 DEG with a substrate; rotating the substrate so that the grating structure and the vertical direction have an included angle, and the bottom surface of the substrate faces obliquely upwards; heating the grating structure to soften the grating structure, and the softened grating structure is deformed to be perpendicular to the horizontal plane under the action of gravity; and cooling the grating structure to solidify the grating structure. The preparation process is simple, the yield of the inclined grating can be effectively improved, the nano-imprinting technology is not used, and the manufacturing cost is reduced. The inclined grating prepared by the inclined grating preparation method can achieve the same effect as the grating prepared by the nano-imprinting technology and can be used in AR glasses.

Description

Technical Field

[0001] This invention relates to the field of micro-nano manufacturing technology, and specifically to a method for fabricating tilted gratings. Background Technology

[0002] The concept of the metaverse is gaining increasing popularity, encompassing various aspects of social life and production. Augmented reality (AR) glasses serve as the hardware foundation connecting the real and virtual worlds. Optical waveguide structures based on tilted gratings are considered the most promising optical structure solution for AR glasses. Currently, the main method for fabricating tilted gratings is nanoimprint technology, which suffers from low yield and high cost, limiting the industrialization of AR glasses. Therefore, a new method for fabricating tilted gratings is needed to improve yield and reduce manufacturing costs. Summary of the Invention

[0003] To address the issues of low yield and high cost in existing methods for fabricating tilted gratings, this invention provides a method for fabricating tilted gratings.

[0004] The technical solution adopted by this invention to solve the technical problem is as follows:

[0005] A method for fabricating a tilted grating, comprising:

[0006] Fabricate a grating structure on the substrate at a 90° angle to the substrate;

[0007] Rotate the substrate so that the grating structure and the vertical direction are at an angle, and the bottom surface of the substrate faces diagonally upward;

[0008] Heating the grating structure softens it, and the softened grating structure deforms to be perpendicular to the horizontal plane under the action of gravity.

[0009] Cool the grating structure until it solidifies.

[0010] A tilted grating, wherein the tilted grating is prepared using the tilted grating preparation method described above.

[0011] The beneficial effects of this invention are:

[0012] The present invention provides a simple fabrication method for tilted gratings, which can effectively improve the yield of tilted gratings; it does not employ nanoimprint lithography, thus reducing manufacturing costs. The tilted gratings fabricated using the method of the present invention achieve the same effect as gratings fabricated using nanoimprint lithography and can be used in AR glasses. Attached Figure Description

[0013] Figure 1 This is a flowchart of a method for fabricating a tilted grating according to the present invention.

[0014] Figure 2This is a sample structure diagram obtained in step two of the tilted grating fabrication method of the present invention.

[0015] Figure 3 The sample structure diagram is obtained in step three of the method for fabricating a tilted grating according to the present invention.

[0016] Figure 4 The sample structure diagram is obtained from steps four and five of the method for fabricating a tilted grating according to the present invention.

[0017] Figure 5 This is a schematic diagram of a multilayer grating structure for a tilted grating fabrication method according to the present invention.

[0018] In the figure: 1. Substrate, 2. Grating structure, 21. First grating layer, 22. Second grating layer. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0021] Example 1

[0022] This embodiment provides a method for fabricating a tilted grating, including:

[0023] S1. Fabricate a vertical grating structure 2 on the substrate 1. At this time, the vertical angle of the grating structure 2 becomes 0 degrees.

[0024] S2. Rotate the base 1 so that the bottom surface of the base 1 faces the oblique upward and the grating structure 2 and the vertical direction have an angle that is not 0° and is not 90°.

[0025] S3. Heating the grating structure 2 softens the grating structure 2. The softened grating structure 2 deforms under the action of gravity until the grating structure 2 is perpendicular to the horizontal plane, that is, the angle between the grating structure 2 and the vertical direction becomes 0 degrees.

[0026] S4, Cooling grating structure 2 until grating structure 2 is cured.

[0027] The number of times S2 to S4 are executed is not limited.

[0028] This embodiment presents a simplified process for fabricating tilted gratings. The process is simple and can effectively improve the yield of tilted gratings. It does not employ nanoimprint technology, thus reducing manufacturing costs.

[0029] The tilted grating prepared by the tilted grating preparation method of the present invention can achieve the same effect as the grating prepared by nanoimprint technology and can be used in AR glasses.

[0030] Example 2

[0031] This embodiment provides a method for fabricating a tilted grating, such as Figure 1 The specific steps are as follows:

[0032] Step 1: Prepare substrate 1. Substrate 1 is a thin sheet structure, usually made of high-refractive-index glass, which functions as an optical waveguide.

[0033] Step 2: Fabricate a grating structure 2 perpendicular to the top surface of substrate 1, as shown below. Figure 2 The angle between the grating and the substrate 1 is 90°;

[0034] Step 3: Rotate base 1 until its bottom surface (lower surface) faces diagonally upwards. At this point, the bottom surface of base 1 forms an angle θ with the horizontal plane, as shown below. Figure 3 As shown, there is an angle θ between grating structure 2 and the vertical direction;

[0035] Step 4: Heat the sample using pulse heating to soften the grating structure 2. Under the influence of gravity, the grating structure 2 becomes vertical, and the angle between the grating structure 2 and the substrate 1 changes from 90° to 90°-θ. Figure 4 As shown. Optionally, the sample (grating structure 2 and substrate 1) can be heated in a vacuum environment to reduce the capillary force between the gratings.

[0036] The above-described pulse heating method is merely an example. Step 5: Cool the grating structure 2 and solidify it to obtain a tilted grating. At this point, the angle between the grating structure 2 and the substrate 1 is 90°-θ, meaning that the grating structure 2 of the tilted grating is not perpendicular to the substrate 1.

[0037] Optionally, a cooling device is located on one side of the grating structure 2, and cools the grating structure 2 by blowing out cold air. This embodiment does not limit whether the grating structure 2 remains in a vacuum environment during the cooling process.

[0038] Optionally, the grating is composed of multiple layers of resin, and the grating structure 2 is a multilayer grating structure 2. For example... Figure 5 As shown, Figure 5 (a) is a two-layer grating structure 2. Figure 5 (b) is a four-layer grating structure 2. The multilayer grating structure 2 includes grating units, with at least one grating unit. If the number of grating units exceeds one, the grating units are stacked sequentially, such as... Figure 5(b) consists of two stacked grating units, with the bottommost grating unit located on substrate 1. Each grating unit includes a first grating layer 21 and a second grating layer 22. The first grating layer 21 is located below the second grating layer 22. The first grating layer 21 and the second grating layer 22 are made of different materials; the melting point of the first grating layer 21 is lower than that of the second grating layer 22. The heating temperature in step four is higher than the melting point of the first grating layer 21 but lower than the melting point of the second grating layer 22.

[0039] Example 3

[0040] To avoid excessive tilting of the θ angle, which could damage the grating, the tilting-heating-cooling process can be performed multiple times, each time creating an angle of θ / N, where N is the number of operations. Therefore, this embodiment provides a method for fabricating a tilted grating, including the following steps:

[0041] Step 1: Prepare substrate 1. Substrate 1 is a thin sheet structure, usually made of high-refractive-index glass, which functions as an optical waveguide.

[0042] Step 2: Fabricate a grating structure 2 perpendicular to the substrate 1 on the substrate 1, with the grating and the substrate 1 having an angle of 90°.

[0043] Step 3: Rotate the substrate 1 until there is an angle θ / N between the grating structure 2 and the vertical direction, at which point the bottom surface of the substrate 1 faces diagonally upward;

[0044] Step 4: Heat the sample to soften the grating structure 2. Under the action of gravity, the grating structure 2 becomes vertical.

[0045] Step 5: Cool grating structure 2 until it cures.

[0046] Step 6: Repeat steps 3 to 5 until step 5 is executed N times in total, and the tilted grating is completed.

[0047] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0048] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with this application should be covered within the scope of protection of this application.

Claims

1. A method for fabricating a tilted grating, characterized in that, include: A grating structure (2) with an angle of 90° to the substrate (1) is fabricated on the substrate (1); Rotate the base (1) so that there is an angle between the grating structure (2) and the vertical direction, and the bottom surface of the base (1) faces obliquely upward; Heating the grating structure (2) softens the grating structure (2), and the softened grating structure (2) deforms to be perpendicular to the horizontal plane under the action of gravity; the heating of the grating structure (2) is carried out by pulse heating. Cool the grating structure (2) until the grating structure (2) is cured; The grating structure (2) includes a grating unit, which includes a first grating layer (21) and a second grating layer (22). The first grating layer (21) is located below the second grating layer (22). The melting point of the material of the first grating layer (21) is lower than the melting point of the material of the second grating layer (22). The temperature when heating the grating structure (2) is higher than the melting point of the material of the first grating layer (21) and lower than the melting point of the material of the second grating layer (22).

2. The method for fabricating a tilted grating as described in claim 1, characterized in that, The steps of rotating base (1), heating grating structure (2) and cooling grating structure (2) are performed sequentially multiple times until the tilt angle of grating structure (2) meets the requirements.

3. The method for fabricating a tilted grating as described in claim 1, characterized in that, The heating grating structure (2) is performed in a vacuum environment.

4. A tilting grating, characterized in that, The tilted grating is prepared using a tilted grating preparation method as described in any one of claims 1 to 3.

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